Lift apparatus

ABSTRACT

An elevator having a carriage moving up and down a track attached to an upright structure. A winch mounted on the structure adjacent one side of the track is connected to a cable trained over an idler pulley assembly adjacent the top of the track and connected to the carriage. The winch has drums connected to a drive unit and a device for sensing the tension on the cable which is operable in response to a reduction of load tension on the cable to stop the winch and maintain the cable on the winch drums. The drive unit has an electric motor and brake that is automatically applied when the motor is not operating. Brakes mounted on the carriage cooperate with the track to lock the carriage to the track in the event there is a reduction in tension on the cable or a break in the cable. The carriage brakes can also be manually actuated.

United States Patent [1 1 Buschbom et al.

[111 3,887,038 [451 June 3, 1975 1 1 LIFT APPARATUS [73] Assignee: Veda, 1nc., Long Lake, Minn.

[22] Filed: Jan. 19, 1973 [21] Appl. No.: 325,173

[52] US. Cl. 187/27; 187/6; 187/87; 254/175 [51] Int. Cl B66b 5/12 [58] Field of Search 187/6, 11, 22, 27, 20, 187/87; 254/168, 172, 175; 242/57, 54 R [56] References Cited UNITED STATES PATENTS 1,360,652 11/1920 Levedahl 254/175 2,564,267 8/1951 Manke 254/175 3,182,961 5/1965 Le Bus... 254/175 3,517,774 6/1970 Meyer.... 187/27 3,625,373 12/1971 Hu1l.... 188/170 3,672,471 6/1972 Badding 187/27 3,690,412 9/1972 Murray et a1 187/20 3,757,897 9/1973 Moulson et a1. 187/6 Primary Examiner-Evon C. Blunk Assistant Examiner-Jeffrey V. Nase [57] ABSTRACT An elevator having a carriage moving up and down a track attached to an upright structure. A winch mounted on the structure adjacent one side of the track is connected to a cable trained over an idler pulley assembly adjacent the top of the track and connected to the carriage. The winch has drums connected to a drive unit and a device for sensing the tension on the cable which is operable in response to a reduction of load tension on. the cable to stop the winch and maintain the cable on the winch drums. The drive unit has an electric motor and brake that is automatically applied when the motor is not operating. Brakes mounted on the carriage cooperate with the track to lock the carriage to the track in the event there is a reduction in tension on the cable or a break in the cable. The carriage brakes can also be manually actuated.

32 Claims, 19 Drawing Figures R JHETFHJM: 3 ms SHEET 1 LIFT APPARATUS BACKGROUND OF THE INVENTION Elevator devices have been proposed for use with tower silos to carry personell and equipment up and down the silo. Brott discloses in US. Pat. No. 2,78 l ,865 a silo elevator having a counterbalanced carriage movable on tracks up and down the chute of the silo. The carriage is moved by the effort of the workman on the carriage. Badding shows in U.S. Pat. No. 3,672,471 a silo elevator having a carriage carrying a winch attached to a double suspension cable. The winch selectively operates to wind and unwind the cable to move the carriage up and down the chute of the silo.

The silo chute is used as a passage to enclose the silo doors and for carying ensilage to the base of the silo. Moist air from the feed room at the base of the silo chute blows up the chute. Ensilage and frost accumula' tion due to the moist air in the silo chute and on the carriage present problems which immobilize the prior art elevators. The carriage can jam and stick on the tracks. The winch will continue to operate to undwind the cable supporting the carriage. The carriage may work itself loose whereby the carriage will free fall until the cable is tight. Safety brakes have been used to lock the carriage so its descent can be controlled. For maximum safety, the cable connected to the carriage should remain at all times under tension and in event of a cable failure the carriage should lock in position with a minimum of movement.

SUMMARY OF THE INVENTION A lift or elevator apparatus is used with a structure, as a tower silo, to carry personnel and equipment up and down the structure. The lift apparatus has a carriage mounted for movement on upright track means. Connecting means attach the track means to the structure. The connecting means include adjusting brackets which enable adjustment of the position of the track means relative to the structure. This adjustment allows the same brackets and track means to be used with different designs and types of structures. The carriage is moved on the track means with a winch means mounted on the structure adjacent one side of the track means. The winch means is connected to the carriage with the cable means extended over an idler pulley assembly mounted on the structure at the upper end of the track means. The idler pulley assembly is reversible so that the winch means can be mounted on the structure on either side of the track means. The winch means has a reversible drive whereby the carriage is pulled up the track means and allowed to move down the track means. The drive has a safety brake which is automatically applied when the power to the drive is terminated. The position of the cable means between the winch means and the idler pulley means is controlled with a cable guide means attachable to the structure. The winch means includes means to sense the tension on the cable means due to the carriage and stop the operation of the winch means in response to a reduction in load or carriage tension on the cable means and maintain the cable means in tension thereby to hold the cable means in operative relation with the wmch means. Additional brake means are mounted on the carriage to lock the carriage to the track means in the event that there is slack in the cable or a break in the cable. The brake means are held in release position by the tension in the cable. The brake means on the carriage can be manually operated.

An object of the invention is to provide a lift apparatus which can be safely used with structures as tower silos to carry personnel and equipment up and down the structure. A further object of the invention is to provide a lift apparatus which has track structure that can be used in conjuction with different types and designs of structures and used in a vertical chute of a silo. Another object of the invention is to proivde a winch means having a cable tension sensing device which is operative to terminate the drive of the winch means in the event there is slack in a cable and maintain the cable in tension whereby the cable remains in operative relation with the winch means. A further object of the invention is to proivde a winch means with a drive means having a brake that is self-energizing in one direction of operation of the winch means. Another object of the invention is to provide a motor control system which can be locked on a carriage of a lift apparatus to prevent operation of the control system to prevent accidental operation of the lift apparatus.

IN THE DRAWINGS FIG. 1 is a front elevational view of a tower silo equipped with the lift apparatus of the invention;

FIG. 2 is an enlarged sectional veiw taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an inside elevational view of adjacent ends of the track sections of the track of the lift apparatus;

FIG. 5 is a front elevational view of the carriage of the lift apparatus;

FIG. 6 is an enlarged and foreshortened sectional view taken along the line 66 of FIG. 5;

FIG. 7 is an enlarged sectional view taken along the line 7-7 of FIG. 5;

FIG. 8 is a front elevational view of the idler pulley assembly on the upper section of the structure;

FIG. 9 is a top plan view of FIG. 8;

FIG. 10 is an enlarged sectional view taken along the line 10l0 of FIG. 1;

FIG. 11 is a front elevational view of the winch assembly of the lift apparatus;

FIG. 12 is an end elevational view of the right end of FIG. 11;

FIG. 13 is an enlarged sectional view taken along the line l3-13 of FIG. 12;

FIG. 14 is an enlarged end view taken along line l4-l4 of FIG. 11 with the cable in tension;

FIG. 15 is a view similar to FIG. 14 with a slack cable;

FIG. 16 is a diagrammatic view of the electrical and mechanical system of the lift apparatus;

FIG. 17 is an enlarged side view taken along line 17-17 of FIG. 16;

FIG. 18 is an enlarged plan view of the manual lock for the cable operating the motor control; and

FIG. 19 is a sectional view taken along the line 19-19 of FIG. 18.

Referring to the drawings, there is shown in FIG. I a conventional tower silo indicated generally at 10 for storing ensilage. Silo 10 is a cylindrical upright structure having a plurality of vertically aligned doors 12 providing access to the interior of the structure. A plurality of cylindrical rods or hoops l3 surround the structure to reinforce the cylindrical wall of the structure. An upright generally U-shaped chute 14 encloses the doorways and provides a passageway for directing the silage to the base of the silo. The top of the silo is closed with a roof 16.

The lift apparatus or elevator of the invention, indicated generally at 17, is attached to the silo 10 and functions to carry equipment and personnel up and down the silo. Lift apparatus 17 can be used with other types of structures and can be mounted on either the inside or outside of the structure. The following description is directed to tower silo equipped with lift apparatus l7.

Lift apparatus 17 comprises a carriage 18 mounted for generally vertical movement on an upright track assembly 19. Track assembly 19 is attached to the silo l and extends upwardly in the chute 14. The track assembly can be mounted on silo outside of chute 14. A winch assembly, indicated generally at 20, is mounted on the base of the silo outside of the chute l4 laterally of the track assembly 19. The winch assembly 20 may be mounted on the silo on either side of the track assembly 19. A cable 21 is connected to the winch assembly 20 and carriage 18. The cable 21 has cable sections 21A and 213 coupled to the winch assembly 20. Midportions of cable 21 cooperate with the top idler pulley assembly, indicated generally at 22, to direct the cables downwardly to the carriage 18. On operation of the winch assembly 20, the cable 21 will be moved to elevate the carriage 18 up the chute 14 in an elongated path defined by the track assembly 19. The carriage is lowered by reversing the winch assembly 20 whereby the weight carrriage 18 moves the carriage down the track assembly 19 to the base of the silo 10.

Referring to FIGS. 1 and 2, the track assembly 19 has a pair of upright tracks 23 and 24 extended upwardly into the chute 14 to the top of silo 10. Tracks 23 and 24 are identical in construction and have open sides which face each other. Track 24 has an inner flange 26 and an outer flange 27 separated from flange 26 to define an upwardly directed passageway or guideway 59. Flanges 26 and 27 are connected with a stepped base 28. The base 28 has an outwardly directed step portion 29 which forms an elongated linear upright groove 30. A plurality of spacer rods 32 are attached to tracks 23 and 24 to fit the lateral space between the tracks. Each spacer rod 32 has end ears 34 located adjacent the out side of the stepped portions 29 of the tracks. FIG. 2 shows one-half of spacer rod 32 and track 24. The other half of spacer rod 32 and track 23 is identical in construction. Fasteners 37, as nut and bolt assemblies, attach the ears 34 to the tracks. The fasteners 37 extend through suitable holes in the stepped portion 29 of the tracks and have heads which are located in the upright grooves 30 so that they do not interfere with any portion of the moving carriage 18.

Referring to FIG. 4, there is shown track 24 having two sections 24A and 24B longitudinally aligned with each other to make a continuous track. Both tracks 23 and 24 are made of a plurality of end-to-end sections. The sections 24A and 24B are secured in positive alignment with aligning links 31 disposed in groove 30. Fasteners 33, as nut and bolt assemblies, secure the line 31 to sections 24A and 248 respectively. The link 31 has a width equal to the width of groove 30 whereby link 31 cooperates with the track side walls forming groove 30 to make line 31 a longitudinal aligning member and a connecting member.

A plurality of connector assemblies, indicated generally at 38 in FIGS. 2 and 3, attach the tracks 23 and 24 to the hoops 13 surrounding the silo l0. Connector assembly 38 has a bracket 39 having an elongated longitudinal slot 41. A fastener 42, as a nut and bolt assembly, projects through slot 41 and a suitable hole in the stepped portion 29 of track 24. The head of the fastener 42 is located in groove 30 so that it does not interfere with the movement of carriage l8. Bracket 39 has a laterally disposed leg or projection 43 having a hole for an attaching means, shown as a J-bolt 44. J-bolt 44 has a hook portion extended about hoop 13 so that the J-bolt can be mounted on hoop 13 in any selected angular position. A nut 46 threaded on .l-bolt 44 clamps the leg 43 into engagement with hoop 13. In use, the slot 41 of bracket 39 permits track 24 to be mounted in a selected spaced relation relative to the silo 10. The J-bolt 44 permits the bracket 39 to be angularly located as it can extend upwardly, downwardly or project horizontally, as shown in FIG. 3, to attach the track 24 to the structure. The holes in stepped portion 29 of the track are punched at the factory and may not be aligned with a hoop. The adjustable connector assembly 38 through the slot 41 and angularly movable J -bolt 44 allows the track to be attached to the silo without drilling additional holes or welding the brackets to the track. Common brackets and J-hooks are usable to mount the tracks on different types of structures in selected spaced relationships relative to the walls of the structures. Other types of attaching means may be used to mount the connector assemblies 38 to structures, as silos, that do not have hoops or similar engageable means.

Referring to FIG. 5, carriage 18 has a pair of upright side frame members 47 and 48 located adjacent tracks 23 and 24 respectively. A plurlaity of cross bars 49 are secured to the frame members 47 and 48 to proivde a generally rectangular rigid frame assembly. The top cross bar has an upwardly directed transverse rib 51. A weight 52 having a transverse slot accommodating the rib 51 is supported on the rib and attached thereto with a set screw 52A. Weight 52 provides the carriage with additional weight so that it will move down the tracks 23 and 24 when the cable 21 is unwound from the winch assembly 20.

A pair of rollers or wheels 53 and 54 rotatably mount the upper and lower portions of side frame member 47 on the track 23. In a similar manner, a pair of rollers or wheels 56 and 57 rotatably support the side frame member 48 on the track 24. As shown in FIG. 2, the roller 56 is rotatably mounted on an axle secured to a rearwardly directed arms 58 attached to the side frame member 48. A similar rearwardly directed arm carrying an axle rotatably carries the roller 53. The roller 56 is located in upright guideway 59 formed by the flanges 26 and 27 of the track 24. Rollers 53 and 54 move in the guideways of track 23.

Secured to the upper portion of the side members 47 and 48 is a transverse plate 60. A pair of laterally spaced outwardly directed stub axles 61 and 62 are secured to plate 60. Equalizer pulleys 63 and 64 are rotatably mounted on the stub axles 61 and 62 respectively. The cable 21 is trained under the pulleys 63 and 64 and extends upwardly to the idler pulley assembly 22 mounted on top of the structure. Pulleys 63 and 64 allow limited movement of the cable sections 21A and 218 to accommodate for unequal winding of the cable by the winch assembly 20 and maintain substantially the same load tension on the cable sections. Cable 21 has a first section 21A extended upwardly from pulley 63 through a hole in ear 66 attached to the side frame member 47. Section 21B of the cable extends upwardly from pulley 64 through a hole in ear 67 attached to the side frame member 48. A first stop or abutment 69 is secured to the cable 21A below ear 66. In a similar manner, a second stop or abutment 71 is secured to the cable 218 below ear 67. The abutments 69 and 71 may be cable clamps and function as stops or anchors to prevent the cable from separating from carriage 18 in the event of cable breakage. Stops 69 and 71 will anchor on the ears 66 and 67 to thereby prevent the carriage 18 from falling if there is a cable failure.

Carriage 18 has a pair of brakes, indicated generally at 72 and 73, which anchor on the tracks 23 and 24 respectively. Brakes 72 and 73 are automatically and simultaneously actuated when there is a slackening or rupture in the cable 21. Brakes 72 and 73 can also be manually actuated. The brakes 72 and 73 are identical in sturcutre and function. The following description is limited to brake 72 shown in FIGS. 6 and 7.

Brake 72 has a plate or support member 74 attached with fasteners 76 to the lower portion of side frame member 47. The plate member 47 extends adjacent the inside of track 23. The inner end of platemember 74 has an outwardly directed back or shoe 77 located adjacent the flange 26 of the track 23. The upper and lower portions or ends 78 and 79 of the back 77 project outwardly and away from the flange 26. An eccentric cam or member 81 is located within the guideway 59 between flanges 26 and 27 of track 23. The cam 81 is fixed to a drive shaft 82 rotatably mounted on plate member 74. An arm or lever 83 is attached to shaft 82 to control the angular position of the cam 81. The cam 81 is moved in the direction of arrow 84 to apply the barke on downward movement of arm 83. Once the brake is initially applied, it will continue to rip and hold the carriage in a locked position on the track 23. The cam 81 operates in a selflocking direction, as shown by arrow 84.

The arm 83 of the brake is moved with an actuator mechanism indicated generally at 86. The actuator mechanism 86 can be manually moved to apply the brakes 72 and 73 and is automatically applied in response to a loss or reduction in tension of the cable 21 between the equalizer pulleys 63 and 64. Actuator mechanism 86, shown in FIG. 5, comprises a cross bar 87 extended between the side frame members 47 and 48. A U-shaped member 88 is secured to cross bar 87 to provide a handle to manually apply the brakes 72 and 73 by moving the cross bar 87 in a downward direction.

An upwardly directed rod 89 is attached to the midsection of cross bar 87. The rod 89 has a forwardly directed projection or leg 91 extended through an upright slot 92 in the plate 60. A small pulley 93 is rotatably mounted on leg 91 and engages the portion of the cable 21 extended between pulleys 63 and 64. The tension on the cable moves the pulley and cross bar 87 in an upward direction, thereby holding the brakes 72 and 73 in the release position.

As shown in FIG. 6, an upright sleeve 94 is attached to the end of cross bar 87. An upright rod 96 is attached to the sleeve 94. Rod 96 extends downwardly adjacent the side frame member 47 and has an end portion 97 pivotally connected to the end of the arm 83.

The rod 96 is biased in a downward direction with a 5 coil spring 99 located around rod 96. The spring 99 has an upper end abutting against a bracket 98 fixed to side member 47. The lower end of spring 99 abuts against a stop 101 secured to rod 96. The spring 99 biases the rod 96 in a downward direction, as indicated by arrow 102, biasing the arm 83 in the direction to apply the brake. The tension on cable 21 acting on pulley 93 holds the rod 96 in the up position against the biasing force of the spring 99. A similar rod and spring construction is located adjacent side member 48 and attached to the opposite end of cross member 87. This rod actuates the brakes 73.

An outwardly projected plateform 103 is pivotally connected to the lower portion of side frame members 47 and 48. The platform has an open floor 104, as an expanded metal member, and an upright outerperipheral wall 105. The platform 103 is of a size and shape corresponding substantially to the cross sectional shape of the passageway formed by chute 14. Pivots 106 connect the platform 103 to brackets 107 fixed to the side frame members 47 and 48. The platform 103 can be rotated in an upward direction adjacent the frame assembly of the carriage so that it does not interfere with movement of particulate material discharged from the silo and movement of equipment, silo doors and personnel past the platform 103. A latch (not shown) holds the platform 103 in its up position.

ldler pulley assembly 22, shown in FIGS. 8 and 9, has a mount 111 attached to the upper part of the silo adjacent the upper end of the track assembly 19. Mount 111 comprises a pair of spaced upright angle members 112 and 113 having top portions or legs 114 and 116 engaging the top of the side wall of silo 10. A plurality of fasteners 117, as U-bolts, secure the angle members 112 and 113 to hoops 13 to fix the position of the idler pulley assembly on the silo 10.

A first generally flat transverse support 118 is connected to angle member 112. A similar support 119 is connected to angle member 113. Supports 118 and 119 are horizontally aligned with each other and carry a transverse frame 121. Fram 121 has a base plate 121A having transverse slots 122. Fasteners 123, as nut and bolt assemblies, attach the base plate 121A to the sup ports 118 and 119. The slots 112 permit the base plate 121A to be transversely adjusted relative to mount 111 and reversed end-for-end on the mount 111. A front plate 124 connected to base plate 121A carries a pair of laterally spaced outwardly projected axles or rod members 126 and 127. A first idler pulley 128 is rotat ably mounted on axle 126. Second and third pulleys 129 and 131 are rotatably mounted on axle 127. Cable 21A is trained over pulleys 128 and 129. Cable 21B is trained over pulley 131. A plurality of fingers 132 mounted on plate 124 project outwardly adjacent the outer peripheral edge of pulley 128 to prevent the cable 21A from disengaging or jumping off of pulley 128. Similar fingers 133 mounted on plate 124 project outwardly adjacent the outer peripheral edges of pulleys 129 and 131 to prevent cables 21A and 213 from disengaging or jumping from pulleys 129 and 131.

The pulleys 128, 129 and 131 are laterally adjustable by changing the position of base plate 121A relative to supports 118 and 119. This lateral adjustment enables the cable take-up side of the pulleys 128 and 131 to be vertically aligned with the carriage to minimize lateral forces on the carriage. The lateral positons of the pulleys 128 and 131 are adjusted to located the cable sections 21A and 218 in vertical positions. The frame 121 when reversed or positioned end-for-end on mount 111 reverses the positions of pulleys 128 and 129, 131 so that the winch assembly can be mounted on the opposite side of track assembly 19, as shown in broken lines in FIG. 1.

Referring to FIGS. 1 and 10, the cables 21A and 21B extending down from idler pulley assembly 22 project through cable position control means indicated at 135. Cables 21A and 218 may have been 60 to 100 or more feet extension exposed to the wind on the outside of silo 10. The wind may twist and whip the cables if they are not restrained. Under some conditions this may be severe enough so that it will cause the carriage 18 to e continuously jerked up and down placing shock loading on the carriage 18, the track means 19, the winch assembly 20, the idler pulley assembly 22, and the cable 21.

The cable position control means 135 has a pair of laterally spaced rods 136 and 137. Brackets I38 and 139 are attached to the opposite ends of rods 136 and 137. Fasteners 141, as .l-bolts, U-bolts, and the like, secure the brackets 138 and 139 to a hoop 13 located about one-third up the silo. The fasteners are adjusted to locate the rods 136 and 137 at a slight upwardly and outwardly incline to accommodate the angle of the cables 21A and 21B.

As shown in FIG. 10, a center block or member 142 is secured to both rods 136 and 137. Block 142 separates the space between the rods 136 and 137 into two separate elongated slots 143 and 144. Cable 21A projects through slot 143 and is guided for lateral movement therein by rods 136 and 137. Cable 218 projects through slot 144 and is guided for lateral movement therein by rods 136 and 137. Block 142 keeps cables 21A and 21b in their respective slots.

Winch assembly 20, shown in FIGS. 11 and 12, has a frame comprising a pair of generally upright angle members 201 and 202. A plurality of U-bolts 203 attach the angle members to the adjacent hoops 13 on the silo 10. Angle members 201 and 202 are connected to the hoops 13 to locate the winch assembly 20 at a slight angle relative to a horizontal plane. The cable take-up drums 207 and 208 of the winch assembly 20 are inclined upwardly away from the outside of track assembly 19. In other words, the axis of rotation of the drums 207 and 208 is inclined so that the outer ends of the drums 207 and 208 are at a higher level than the drum ends facing the tack assembly. The inclination of drums 207 and 208 aligns the cable sections 21A and 21B with the drums 207 and 208 in a manner so that the cables are generally normal to the axis of rotation of the drums to insure even winding of cables on the drums. A first outwardly directed plate 204 is attached to angle member 201. A second outwardly directed plate 206 is attached to angle member 202. A pair of axially aligned cable take-up drums 207 and 208 are located between the plates 204 and 206. The drums 207 and 208 are mounted on a common transverse shaft 209 extended between plates 204 and 206. A bearing 211 mounts one end of shaft 209 on the plate 204. The opposite end of shaft 209 is coupled to a power transmission unit 212 secured to plate 206. The

drums 207 and 208 are identical in diameter and length and have spiral outer peripheral grooves to accommodate the cable sections 21A and 218 The cables sections 21A and 21B are aligned on the drums 207 and 208 in a single layer whereby the same lengths of cable are simultaneously wound on each drum.

An electric motor 213 is located below drum 208. Motor 213 transmits power to the transmission 212 via a belt and pulley drive 214. the belt and pulley drive 214 is coupled to the input shaft 216 of transmission 212. Motor 213 is mounted on an upright support 217. The lower end of support 217 is pivotally mounted on an outwardly directed axle 218. An adjusting bolt 219 on the upper end of support 217 engages the fixed frame member 202 to move the motor 213 away from the transmission 212 and thereby provides for adjusting the tension of the belt and pulley drive 214. Motor 213 is a reversible electric motor in that it an be driven in either direction of rotation to either wind cable on the drums 207 and 208 or unwind cable from the drums.

Referring to FIGS. 12 and 13, there is shown the brake indicated generally at 221 operable to apply a holding force on the input shaft 216 of transmission 212. Brake 221 is a spring applied solenoid release brake. The solenoid is energized simultaneously with the motor 213 to release the brake. When the motor 213 is off or de-energized, the brake is automatically applied thereby holding both drums 207 and 208 in fixed positions. Brake 221 comprises a pulley or rotor 222 fixed to shaft 216 with a key or suitable attaching mans. The pulley 222 has a circumferential V-groove that accommodates a flexible band 223. The band has a cross sectional shape similar to a V-belt and is of a size to frictionally fit into the outer peripheral groove of the pulley 222. One end of the band 223 is attached to a fixed support 224 with a clamp 226. Other types of attaching structure can be used to anchor the end of band 223. The opposite end of band 223 is attached to a bar 227 with a bolt 228. Other types of connecting structure can be used to attach end of band 223 to the bar 227. The band 223 is trained over the pulley 222 and engages approximately one-half or a portion of the pulley. A spring 229 coupled to bar 227 and an anchor bolt 231 biases the band 223 into braking engagement with the pulley 222. Bar 227 is attached to a solenoid 232. Solenoid 232 has a movable member or core 233 connected to one end of bar 227. When the solenoid 232 is de-energized, the spring 229 biases the band 223 in the direction of arrow 234 whereby the band wrap around the pulley 222. The spring 229 biases the band into the pulley 222 in the direction of rotation of the pulley which unwinds cable from the drums 207 and 208. The frictional forces on the band 223 cause the band to dig into the pulley whereby the brake is self-applying in the unwinding or lowering direction of rotation of the drums 207 and 208. When the motor is energized, solenoid 232 is energized. This moves the movable member 223 in the direction of arrow 236 to the dotted line position. The energized solenoid 232 retracts the band 223 from the pulley 222, thereby releasing the brake.

Referring to FIGS. 11 and 12, there is shown a slack cable sensor indicated generally at 240 for detecting a loose or slack cable as the cables 21A and 21B unwind from the drums 207 and 208 to permit the carriage 18 to move downwardly to the base of the structure. In the event that the carriage 18 is struck or is retarded in its downward movement, the cables 21A and 21B will become slack. The continued rotation of the drums 207 and 208 will cause the slack cables to tangle and bunch up on the drums if the motor is allowed to continue to operate. The slack cable sensor 240 operates to turn off the motor in the event that there is a slack in either or both of the cables 21A and 21B and maintains the cables under tension thereby preventing unwinding and loosening of the cables on the drums 207 and 208. When the down movement of carriage 18 is intermittently impeded or slower than the length of cables unwound from the drums, there is intermittent slackening of the cable. Under these conditions, sensor 240 will turn off the maintain the cables 21A and 21B under tensionn and hold the cables on their respective drums. As soon as the carriage load is reapplied to the cables 21A and 21B, the tension on the cables will return the sensor 240 to its inactive position thereby starting motor 213 and releasing the brake 221.

Cable sensor 240 comprises a rod 241 rotatably mounted on a plate 242. The plate 242 is secured to the upper portion of the plate 204. a sleeve 243 is rotatably mounted on one-half of the rod 241. The outer end of sleeve 243 is rotatably mounted on the upper portion of plate 206. The rod 241 and sleeve 243 are located above the drums 207 and 208 and are in generally parallel relation with the shaft 209. An upright neck member 244 is secured to the rod 241. A cross head 246 is connected to the upper end of member 244. Cross head 246 has forwardly directed ears 247 at the opposite ends thereof to confine the cable 21A to the cross head. The cross head 246 has a length substantially the length of the drum 207. Secured to the mid-section of sleeve 243 is an upright neck member 248. The cross head 249 having a length substantially equal to the drum 208 is attached to the upper end of neck member 248. The outwardly directed ears 251 located at opposite ends of the cross head 249 to confine the cable 21B to the length of the cross head 249.

A first switch and biasing mechanism 252 is secured to the end of rod 241 extended outwardly of the sleeve 243. A second switch and biasing mechanism 253 is secured to the outer end of sleeve 243. The switch and biasing mechanisms 252 and 253 are identical in structure and function. The following description is limited to switch and biasing mechanism 252 as shown in detail in FIGS. 14 and 15.

The switch and biasing mechanism 252 has a first plate member 254 secured to a sleeve 256. Sleeve 256 is positioned on rod 241 and is secured thereto with a fastener 257, such as a set screw or the like. Mounted on a lower portion of the first member 254 is a position responsive switch 258, as a mercury switch. When the cable 21A is taut or under tension, the switch 258 is in the closed position allowing the motor 213 to operate to unwind the drums 207 and 208. A second member or link 259 is located adjacent the member 254. A pivot bolt 261 connects an upper portion of member 254 to end portion of bar member 259. A spring 262 is connected to the opposite end of member 259 and a fixed anchor 263 attached to the plate 206. Spring 262 biases the member 259 in the direction of the arrows 264. When the cable 21A is under tension, as shown in FIG. 14, the spring has a torque arm X representing the lateral distance between the axis of rotation or rod 241 and pivot bolt 26].

Referring to FIG. 15, cable 21A has slackened and become loose. The spring 262 biases the cross head 246 in the forward direction of the arrow 266 thereby keeping the cable under tension and holding the cable on the drum 207. The first member 254 pivots in a counter-clockwise direction thereby changing the position of the position responsive switch 258 so that the switch is in the open position. When switch 258 is in the open position, it triggers the control for the motor 213 to run off the motor 213. The lateral distance between the axis of rod 241 and the axis of pivot bolt 261 increases when there is a slackening of the cable as represented by Y. This increases the torque arm and rotation forces applied to the rod 241 and thereby maintains cable 21A sufficiently taut so that it will remain on the durm 207.

The switch and biasing mechanism 253 operates in the same manner in response to the slackening of the cable 21B. Switch, plate, link and spring structure, as shown in FIGS. 14 and 15, are connected to sleeve 243 to sense the tension in cable section 21B and maintain cable section 21B taut when the load is released from the cable section.

Referring to FIG. 16, there is shown a schematic diagram of the electrical control and mechanical system of the lift apparatus 17. Carriage 18 movable mounted on track means 19 is connected to the winch assembly 20 with cable 21. The winch assembly 20 includes a drive unit having a motor 213 drivably connected to the winch drum 207 and 208 and a brake 221. The motor 213 is electrically coupled to an electric control system 267. The control system 267 has control components that are connected to a source of electric power 268, the solenoid 232 of the brake 221, and the position responsive switches 258 and 258A of the slack cable sensor 240. Control system 267 has a power circuit and a control circuit which coordinates the operation of the solenoid 232 and switches 258 and 258A with the operation of motor 213. When the motor 213 is functioning, the solenoid 232 is energized thereby releasing the brake band 223 from the brake rotor or rotatable member 222 whereby the motor drives the drums 207 and 208. Motor 213 is reversible whereby the winch assembly 20 functions to elevate the carriage l8 and pemits the carriage to move down to the base of the silo.

Electric control system 267 comprises a switch 269 having movable power contacts 270 and 271 selectively operable to engage separate contacts connected to brake solenoid 232 and to motor 213 whereby the motor can be operated in forward and reverse directions. Brake solenoid 232 is only energized when power is supplied to motor 213. Accordingly, the brake 221 is always applied when the motor 213 is not operating.

The control circuit has a transformer 272 to provide low voltage to switches 258 and 258A and brake solenoid 232. Transformer 272 is connected to a three position switch 273 operated with a cable or rope 274. Switch 273 has an acutator 275, as a pulley, connected to cable 274 movable to operate the switch. Switch 273 is normally open or off. When cable 274 is raised, the switch 269 is closed to operator motor 213 in the carriage up direction. When cable 274 is moved down, switch 269 is closed to reverse the operation of motor 213 to permit the carriage to move down. Stops 276 attached to upper and lower sections of cable 274 are engaged by carriage 18 to automatically move the cable 274 to return actuator 275 to its neutral position. Actuator 275 will also automatically move to the neutral position when the holding forces on cable 274 are released.

Switch 273 is electrically coupled to a pair of control solenoids 277 of switch 269 in a manner to selectively energize the control solenoids thereby controlling the direction of drive of motor 213. sensor switches 258 and 258A are connected in series with each other in series with each control solenoid. Both sensor Sensor 258 and 258A must be closed before power is supplied to control solenoids 277.

Manual lock 280 is mounted on side frame member 48 laterally of brake applying handle 88 where it can be readily operated by a man standing on platform 103. As shown in FIGS. 18 and 19, lock 280 has a base 281 carrying vertically spaced ears 282 and 283. Ears 282 and 283 have aligned holes 284 accommodating motor control cable 272. Cable 272 is held in engagement with base 281 by a short foot or bar 286. An overcenter linkage 287 holds foot 286 against cable 272 to prevent movement of the cable. This eliminates accidental actuation of the winch motor 213 and resultant movement of carriage 18.

Over-center linkage 287 has a first member 288. A pivot pin 289 pivotally connects one end of first member 288 to a U-shaped support 291 attached to base 281. An outwardly projected control arm 292 has bifurcated portions extended over the first member 288 and pivotally connected to support 291 with pivots 293. Arm 292 has a stop 294 engageable with member 288 to limit its upward or lock motion. A link 295 pivotally connects the mid-portion of member 288 with arm 292 whereby the angular position of member 288 is controlled by moving arm 292. The foot 286 is attached to a rod 296 ad justably connected to the upper end of member 288. ln use, the arm 292 and link 295 has an over-center action which locks the foot 286 in tight engagement with cable 272. Stop 294 limits the over-center upward movement of arm 292, as shown in FIG. 19. The foot 286 is released from the cable 272 by moving arm 292 down in the direction of arrow 297.

In operation, to lift carriage 18 in an upward direction to carry personnel to the top of the structure, the lock 280 is initially released. This permits the control cable 274 to be moved. Cable 274 is raised, thereby moving the acutator 275 of the system control switch 273 in an upward direction. This energizes the solenoid control 277 which actuates the switch 269 to connect power to the motor 213 to drive the motor is the forward or cable elevating direction. When the motor is energized, the switch 269 also energizes the solenoid 232 and thereby releases band 223 from the rotatable member 222 of the brake 221. The operating motor 213 drives the winch drums 207 and 208 to wind the cables 21A and 218 on the drums. The carriage 18 will continue to move up as long as there is force being applied to the control cable 274. The operator applies a light friction force on the control cable as he is carried upward by the carriage 18. When the desired elevation is reached, the operator merely releases his grip on cable 274. The actuator 275 will return to its neutral position whereby the switch 269 will move to its neutral position, terminating the electric power to motor 213. The brake solenoid 232 is also de-energized whereby spring 229 will automatically apply the brake 221. As shown in F 1G. 13, the brake band 223 is moved into the pulley 222 by the force of spring 229 in the direction of rotation of the pulley representing the downward direction of movement of the carriage. The band 223 thus is self activating in that any rotation of pulley 222 will further increase the braking force of the band on the pulley.

Before the operator leaves carriage 18, he applies the lock 208 to the cable 274. This prevents movement of the cable 274 so that it cannot be inadvertently actuated by someone at the base of the silo or the operator of the lift apparatus.

The operator can lower carriage 18 by unlocking the lock 280 and applying a downward force on cable 274. This moves actuator 275 in a downward direction to energize a control solenoid 277, thereby moving switch 269 in a direction to apply power to motor 213 so as to drive the drums 207 and 208 in a direction to unwind cables 21A and 21B from the drums 207 and 208.

In the event that the carriage 18 is retarded or struck on tracks 23 and 24, cables 21A and 218 will become slack. If either or both cables 21A and 21B become slack, the cable sensor 240 is actuated to open the control circuit by opening one or both of the position responsive switches 258 and 258A, thereby power to the motor 213. This also de-energizes the brake solenoid 232 whereby the brake 221 is automatically applied. The cable sensor 240 also functions to maintain tension on cable 21A and 21B to hold the cables in operative relation with the drums 207 and 208. When the carriage 18 is free, cables 21A and 21B will again be subjected to load tension. This tension is sufficient to move the slack cable sensor 240 in a position whereby the switches 258 and 258A are in their normally closed position to complete the control circuit. The switches 258 and 258A are a part of a fail safe control circuit of the elevator apparatus. If any portion of the control circuit is broken or shorted out, the motor 213 cannot operate.

The carriage 18 will continue in its downward movement if the operator continues to apply a downward force on cable 274. When carriage 18 is at the base of the structure, the carriage engages the stop 276 on the cable 274 which will return the actuator 275 to the neutral position. A similar stop on cable 274 adjacent the top of the structure is engaged by carriage 18 to automatically return the actuator 275 to its neutral position so that he carriage will not jam on the idler pulley assembly 22.

As shown in F168. 5, 6 and 7, if there is a slackening of cables 21A and 213, the actuator 86 will be moved in a downward direction by springs 99. This moves the brake arms 83 in a downward position and thereby applies the cams 81 into locking engagement with the flanges 26 of tracks 23 and 24. This locks the carriage in a fixed position on traks 23 and 24. The action of springs 99 can be supplemented by applying a force on the handle 88. As soon as tension is restored to cable 21, the cams 81 will be released from tracks 23 and 24, whereby the carriage 18 is free to move downwardly along the tracks.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be stored to falling within the scope of the invention as claimed.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A lift apparatus for use with a structure comprising: a carriage, track means locatable adjacent to the structure for guiding the carriage up and down in a generally upright path, winch means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to the drum means to rotate the drum means, said drive means including a motor operable to selectively rotate said drum means in opposite directions, cable means connected to the drum means and carriage, means adjacent to the upper end of the track means for accommodating the cable means, said cable means extended from the drum means over the means adjacent to the upper end of the track means and to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage means moves downwardly in the upright path, means to sense the load tension of the cable means, said means to sense the tension being operable to stop the motor in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means.

2. The apparatus of claim 1 wherein: said drive means includes an electric motor for selectively driving the drum means in opposite direction, said means to sense the tension on the cable having electric switch means which is closed when the cable means is under load tension and open when there is a slack of the cable means, and electric control means connected to the motor, switch means and a source of electric power operable to terminate power to the motor when the switch means is open.

3. The apparatus of claim 2 wherein: the electric control means includes a means operable to supply power to the motor when the switch means is closed.

4. A lift apparatus for use with a structure comprising: a carriage, track means locatable adjacent to the structure for guiding the carriage up and down in a generally upright path, winch means for moving the carriage, said winch means having rotatable durm means, reversible drive means drivably connected to the drum means to rotate the drum means, cable means connected to the drum means and carriage, means adjacent to the upper end of the track means for accommodating the cable means, said cable means extended from the drum means over the means adjacent to the upper end of the track means and to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage means moves downwardly in the upright path, means means to sense the load tension of the cable means, said means to sense the tension being operable to stop the drive means in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means, said means to sense the tension of the cable means including a movable member having a portion engageable with the cable means at a location spaced from the drum means, biasing 5 means attached to the movable member to bias the portion in the direction to hold the portion in engagement with the cable means and maintain the cable means under tension and on the drum means when there is a reduction of load tension on the cable means, and position responsive switch means operably connected to the movable member to stop the drive means when there is a reduction of load tension on the cable means.

5. The apparatus of claim 4 wherein: said movable member includes an arm, link means pivotally connected to said arm, said biasing means being connected to said link means to bias the link means in a direction whereby the effective torque arm of the arm increases with the amount of reduction in load tension on the cable means.

6. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means and carriage, means mountable on the upper portion adjacent the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum means, over the means adjacent the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, drive means includes a motor operable to selectively rotate said drum means in opposite directions whereby the cable means is selectively wound on and taken off the drum means to move the carriage, means to sense the tension on the cable means due to the load of the carriage, said means to sense the tension being operable to stop the motor in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means.

7. The apparatus of claim 6 wherein: the track means comprise a pair of upright tracks, each track having side flanges and a base, said base having upright groove means for accommodating a portion of the means for attaching the track means to the structure.

8. The apparatus of claim 6 including: means attachable to the structure between the winch means and the means on the upper portion to control the lateral movement of the cable means.

9. The apparatus of claim 6 wherein: the winch means includes support means for the drum means, said support means locating said drum means for rotation about an axis inclined upwardly and away from the track means.

10. The apparatus of claim 6 wherein: the carriage has a pair of pulleys, said cable means being trained over said pulleys, brake means cooperating with the track means operable to lock the carriage to the track means, said means responsive to the tension on the cable means being operable to actuate the brake means when the tension on the cable means is released.

11. The apparatus of claim 10 wherein: the brake means includes eccentric members engageable with the track means when the brake means is applied.

12. The apparatus of claim 10 including: means manually operated to actuate the brake means.

13. The apparatus of claim 6 wherein: the carriage has an equalizer pulley assembly cooperating with the cable means, said cable means having a first section and a second section extended from the equalizer pulley assembly to the pulley means and winch means, said winch means having a first drum portion for the first section of the cable means and a second drum portion for the second section of the cable means.

14. The apparatus of claim 13 including: means for mounting the first drum portion and second drum portion for rotation about an axis inclined upwardly and away from the track means.

15. The apparatus of claim 13 including: said means to sense the tension operable to sense the tension on the first and second sections of the cable means due to the carriage and stop the operation of the winch means in response to a reduction of load tension on either or both sections of the cable means and maintain the cable means in tension and hold the cable means in operative relation with the first drum portion and second drum portion.

16. The apparatus of claim 6 wherein: the means to sense the tension on the cable means comprises means having a portion engageable with the cable means at a location spaced from the drum means, biasing means to bias said portion into engagement with the cable means and maintain the cable means under tension when there is a reduction of load tension on the cable means, and position responsive switch means operable to stop the motor when there is a reduction of load tension on the cable means.

17. The apparatus of claim 6 wherein: said drive means includes brake means operable to hold the drive means when the motor is not operating to prevent rotation of the drum means to hold the carriage in a fixed position on the track means and to release the drive means to allow rotation of the drum means and movement of the carriage relative to the track means when the motor is operating.

18. The apparatus of Claim 17 wherein: said brake means comprises a rotatable member, a flexible band engageable with the rotatable member to prevent rotation of the rotatable member, means anchoring one end of said band, biasing means connected to the other end of the band to bias the band into engagement with the rotatable member to brake the rotatable member, and control means to move the band into a non-braking position when the motor is operating and permitting the biasing means to move the band into braking position into engagement with the rotatable member when the motor is not operating.

19. The apparatus of Claim 18 including: means connecting the biasing means to the band so that the biasing means moves the band into braking position on the rotatable member in the direction of rotation of the rotatable member which lowers the carriage in the upright path whereby the brake means is self-energizing in said direction of rotation of the rotatable member.

20. The apparatus of claim 6 wherein: the means adjacent the upper end of the track means comprises a mount attachable to the upper portion of the structure, a first pulley carrying one section of the cable means and a second pulley carrying another section of the cable means, and means connecting the first and second pulleys to the mount, said last means being laterally adjustable whereby the cable means can be vertically aligned with the carriage.

21. The apparatus of claim 5 wherein: the means adjacent the upper end of the track means comprises a mount attachable to the upper portion of the structure, pulley means for carrying the cable means, a frame supporting the pulley means, and means for removably attaching the frame to the mount, said frame being selectively attached in end-for-end positions on the mount to change the lateral position of said pulley means whereby the winch means can be selectively located on either side of the rack means.

22. The apparatus of claim 21 wherein: said frame is laterally adjustable on the mount whereby the cable means can be vertically aligned with the carriage.

23. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum means over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation on the drive means on the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, said drum means comprising a first drum portion and a second drum portion drivably connected to the drive means, said cable means comprises a first cable attached to the first durm portion and a second cable attached to the second durm portion, means to sense the tension on the cable means including first means to sense the tension on the first cable and operable to stop the drive means in response to a reduction of tension on the first cable and maintain the first cable in tension to hold the first cable in operative relation with the first drum portion, and second means to sense the tension on the second cable and operable to stop the drive means in response to a reduction of tension on the second cable and maintain the second cable in tension to hold the second cable in operative relation with the second drum.

24. The apparatus of claim 23 wherein: the first means to sense the tension on the first cable comprises a rotatable member rotatably mounted generally parallel with the first drum portion, means secured to the rotatable member having a portion engageable with the first cable at a location spaced from the first drum portion, an arm secured to the rotatable means, biasing means attached to the arm to bias the arm in a direction to hold the portion in engagement with the first cable and maintain the first cable under tension when there is a reduction in load tension on the first cable, and position responsive switch means mounted on the arm operable to stop the drive means when there is a reduction in load tension on the first cable and second rotatable member, means secured to the second rotatable member having a portion engageable with the second cable at a location spaced from the second drum portion, an arm secured to the second rotatable means, biasing means attached to the arm to bias the arm in a direction to hold the portion in engagement with the second cable and maintain the second cable under tension when there is a reduction of load tension on the second cable, and position responsive switch means mounted on the arm operable to stop the drive means when there is a reduction of load tension on the second cable.

25. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent to one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the durm means over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, and means to sense the tension on the cable means, said means to sense the tension comprising a movable member having a portion engageable with the cable means at a location spaced from the drum means, biasing means attached to the movable member to bias the portion in a direction to hold the portion in engagement with the cable means and maintain the cable means under tension and on the drum means when there is a reduction of load tension on the cable means, and position responsive switch means operably connected to the movable member to stop the drive means when there is a reduction in load tension on the cable means.

26. The apparatus of claim 25 wherein: said biasing means is connected to said movable member to bais said portion in a direction whereby the effective biasing force increases with the amount of reduction in load tension on the cable means.

27. The appartus of claim 25 wherein: said movable member includes an arm, link means pivotally connected to said arm, said biasing means being connected to said link means to bias the link means in a direction whereby the effective torque arm of the arm increases with the amount of reduction in load tension on the cable means.

28. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent to one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, said drive means including an electric motor for selectively driving the drum means in opposite directions, sensor means to sense the load tension on the cable means resulting from the carriage, said sensor means having electric switch means which is closed when the cable means is under load tension and open when there is a slack in the cable means, and electric control means connected to the motor, switch means and a source of electric power operable to terminate power to the motor when the switch means is open.

29. The apparatus of claim 28 wherein: the electric control means includes a means operable to supply power to the motor when the switch means is closed.

30. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent to the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure comprising a plurality of members, each member having a slot, attaching means angularly adustable relative to the structure for connecting the member to the structure, fastening means extended through said slot and attached to the track means, winch means mountable on the lower portion adjacent 9 the h slde 0f "fink means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably o ne t d t aid d m means to rotate the drum means, cable means conhected the drum e ns and carriage, means mountable Oh the pp Pomofl adjacent to the upper end of the track means for accomr'n d gi h m means, said cable means extended.upwardly from the drum means over the means adjflceht to the upper end of the track means and downwardlv t th carriage h b on operation of the drive m eun i (me di i h drum means rotates to winci'th bl on h d g ar ii h g xd carnage; is moved upwardly in the up- 8 l? on operation of the drive means In the opposite direction the drum means rotates to i d the cable from the drum mea so h h carriage moves downwardly in the urpigh path.

The aPPaTatUS 9 wherein: the track mehhs P P a P of upright tracks, each track having side flanges and a base, said base having upright groove means for accommodating a portion of the wherein: the means for connecting the members to the structure are .l-bolts. 

1. A lift apparatus for use with a structure comprising: a carriage, track means locatable adjacent to the structure for guiding the carriage up and down in a generally upright path, winch means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to the drum means to rotate the drum means, said drive means including a motor operable to selectively rotate said drum means in opposite directions, cable means connected to the drum means and carriage, means adjacent to the upper end of the track means for accommodating the cable means, said cable means extended from tHe drum means over the means adjacent to the upper end of the track means and to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage means moves downwardly in the upright path, means to sense the load tension of the cable means, said means to sense the tension being operable to stop the motor in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means.
 1. A lift apparatus for use with a structure comprising: a carriage, track means locatable adjacent to the structure for guiding the carriage up and down in a generally upright path, winch means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to the drum means to rotate the drum means, said drive means including a motor operable to selectively rotate said drum means in opposite directions, cable means connected to the drum means and carriage, means adjacent to the upper end of the track means for accommodating the cable means, said cable means extended from tHe drum means over the means adjacent to the upper end of the track means and to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage means moves downwardly in the upright path, means to sense the load tension of the cable means, said means to sense the tension being operable to stop the motor in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means.
 2. The apparatus of claim 1 wherein: said drive means includes an electric motor for selectively driving the drum means in opposite direction, said means to sense the tension on the cable having electric switch means which is closed when the cable means is under load tension and open when there is a slack of the cable means, and electric control means connected to the motor, switch means and a source of electric power operable to terminate power to the motor when the switch means is open.
 3. The apparatus of claim 2 wherein: the electric control means includes a means operable to supply power to the motor when the switch means is closed.
 4. A lift apparatus for use with a structure comprising: a carriage, track means locatable adjacent to the structure for guiding the carriage up and down in a generally upright path, winch means for moving the carriage, said winch means having rotatable durm means, reversible drive means drivably connected to the drum means to rotate the drum means, cable means connected to the drum means and carriage, means adjacent to the upper end of the track means for accommodating the cable means, said cable means extended from the drum means over the means adjacent to the upper end of the track means and to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage means moves downwardly in the upright path, means means to sense the load tension of the cable means, said means to sense the tension being operable to stop the drive means in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means, said means to sense the tension of the cable means including a movable member having a portion engageable with the cable means at a location spaced from the drum means, biasing means attached to the movable member to bias the portion in the direction to hold the portion in engagement with the cable means and maintain the cable means under tension and on the drum means when there is a reduction of load tension on the cable means, and position responsive switch means operably connected to the movable member to stop the drive means when there is a reduction of load tension on the cable means.
 5. The apparatus of claim 4 wherein: said movable member includes an arm, link means pivotally connected to said arm, said biasing means being connected to said link means to bias the link means in a direction whereby the effective torque arm of the arm increases with the amount of reduction in load tension on the cable means.
 6. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent one side of the track means for moving the carriage, said winch means having rotatable drum means, reveRsible drive means drivably connected to said drum means and carriage, means mountable on the upper portion adjacent the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum means, over the means adjacent the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, drive means includes a motor operable to selectively rotate said drum means in opposite directions whereby the cable means is selectively wound on and taken off the drum means to move the carriage, means to sense the tension on the cable means due to the load of the carriage, said means to sense the tension being operable to stop the motor in response to a reduction of load tension on the cable means and maintain the cable means in tension and hold the cable means in operative relation with the drum means.
 7. The apparatus of claim 6 wherein: the track means comprise a pair of upright tracks, each track having side flanges and a base, said base having upright groove means for accommodating a portion of the means for attaching the track means to the structure.
 8. The apparatus of claim 6 including: means attachable to the structure between the winch means and the means on the upper portion to control the lateral movement of the cable means.
 9. The apparatus of claim 6 wherein: the winch means includes support means for the drum means, said support means locating said drum means for rotation about an axis inclined upwardly and away from the track means.
 10. The apparatus of claim 6 wherein: the carriage has a pair of pulleys, said cable means being trained over said pulleys, brake means cooperating with the track means operable to lock the carriage to the track means, said means responsive to the tension on the cable means being operable to actuate the brake means when the tension on the cable means is released.
 11. The apparatus of claim 10 wherein: the brake means includes eccentric members engageable with the track means when the brake means is applied.
 12. The apparatus of claim 10 including: means manually operated to actuate the brake means.
 13. The apparatus of claim 6 wherein: the carriage has an equalizer pulley assembly cooperating with the cable means, said cable means having a first section and a second section extended from the equalizer pulley assembly to the pulley means and winch means, said winch means having a first drum portion for the first section of the cable means and a second drum portion for the second section of the cable means.
 14. The apparatus of claim 13 including: means for mounting the first drum portion and second drum portion for rotation about an axis inclined upwardly and away from the track means.
 15. The apparatus of claim 13 including: said means to sense the tension operable to sense the tension on the first and second sections of the cable means due to the carriage and stop the operation of the winch means in response to a reduction of load tension on either or both sections of the cable means and maintain the cable means in tension and hold the cable means in operative relation with the first drum portion and second drum portion.
 16. The apparatus of claim 6 wherein: the means to sense the tension on the cable means comprises means having a portion engageable with the cable means at a location spaced from the drum means, biasing means to bias said portion into engagement with the cable means and maintain the cable means under tension when there is a reduction of load tension on the cable means, and position responsive switch means operable to stop the motor when there is a reduction of load tension on the cable means.
 17. The apParatus of claim 6 wherein: said drive means includes brake means operable to hold the drive means when the motor is not operating to prevent rotation of the drum means to hold the carriage in a fixed position on the track means and to release the drive means to allow rotation of the drum means and movement of the carriage relative to the track means when the motor is operating.
 18. The apparatus of Claim 17 wherein: said brake means comprises a rotatable member, a flexible band engageable with the rotatable member to prevent rotation of the rotatable member, means anchoring one end of said band, biasing means connected to the other end of the band to bias the band into engagement with the rotatable member to brake the rotatable member, and control means to move the band into a non-braking position when the motor is operating and permitting the biasing means to move the band into braking position into engagement with the rotatable member when the motor is not operating.
 19. The apparatus of Claim 18 including: means connecting the biasing means to the band so that the biasing means moves the band into braking position on the rotatable member in the direction of rotation of the rotatable member which lowers the carriage in the upright path whereby the brake means is self-energizing in said direction of rotation of the rotatable member.
 20. The apparatus of claim 6 wherein: the means adjacent the upper end of the track means comprises a mount attachable to the upper portion of the structure, a first pulley carrying one section of the cable means and a second pulley carrying another section of the cable means, and means connecting the first and second pulleys to the mount, said last means being laterally adjustable whereby the cable means can be vertically aligned with the carriage.
 21. The apparatus of claim 5 wherein: the means adjacent the upper end of the track means comprises a mount attachable to the upper portion of the structure, pulley means for carrying the cable means, a frame supporting the pulley means, and means for removably attaching the frame to the mount, said frame being selectively attached in end-for-end positions on the mount to change the lateral position of said pulley means whereby the winch means can be selectively located on either side of the rack means.
 22. The apparatus of claim 21 wherein: said frame is laterally adjustable on the mount whereby the cable means can be vertically aligned with the carriage.
 23. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum means over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation on the drive means on the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, said drum means comprising a first drum portion and a second drum portion drivably connected to the drive means, said cable means comprises a first cable attached to the first durm portion and a second cable attached to the second durm portion, means to sense the tension on the cable means including first means to sense the tension on the first cable and operable to stop the drive means in response to a reduction of tension on the first cable and maintain the first cable in tension to hold the first cable in operative relation with the first drum portion, and second means to sense the tension on the second cable and operable to stop the drive means in response to a reduction of tension on the second cable and maintain the second cable in tension to hold the second cable in operative relation with the second drum.
 24. The apparatus of claim 23 wherein: the first means to sense the tension on the first cable comprises a rotatable member rotatably mounted generally parallel with the first drum portion, means secured to the rotatable member having a portion engageable with the first cable at a location spaced from the first drum portion, an arm secured to the rotatable means, biasing means attached to the arm to bias the arm in a direction to hold the portion in engagement with the first cable and maintain the first cable under tension when there is a reduction in load tension on the first cable, and position responsive switch means mounted on the arm operable to stop the drive means when there is a reduction in load tension on the first cable and second rotatable member, means secured to the second rotatable member having a portion engageable with the second cable at a location spaced from the second drum portion, an arm secured to the second rotatable means, biasing means attached to the arm to bias the arm in a direction to hold the portion in engagement with the second cable and maintain the second cable under tension when there is a reduction of load tension on the second cable, and position responsive switch means mounted on the arm operable to stop the drive means when there is a reduction of load tension on the second cable.
 25. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent to one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the durm means over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, and means to sense the tension on the cable means, said means to sense the tension comprising a movable member having a portion engageable with the cable means at a location spaced from the drum means, biasing means attached to the movable member to bias the portion in a direction to hold the portion in engagement with the cable means and maintain the cable means under tension and on the drum means when there is a reduction of load tension on the cable means, and position responsive switch means operably connected to the movable member to stop the drive means when there is a reduction in load tension on the cable means.
 26. The apparatus of claim 25 wherein: said biasing means is connected to said movable member to bais said portion in a direction whereby the effective biasing force increases with the amount of reduction in load tension on the cable means.
 27. The appartus of claim 25 wherein: said movable member includes an arm, link means pivotally connected to sAid arm, said biasing means being connected to said link means to bias the link means in a direction whereby the effective torque arm of the arm increases with the amount of reduction in load tension on the cable means.
 28. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure, winch means mountable on the lower portion adjacent to one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the upright path, said drive means including an electric motor for selectively driving the drum means in opposite directions, sensor means to sense the load tension on the cable means resulting from the carriage, said sensor means having electric switch means which is closed when the cable means is under load tension and open when there is a slack in the cable means, and electric control means connected to the motor, switch means and a source of electric power operable to terminate power to the motor when the switch means is open.
 29. The apparatus of claim 28 wherein: the electric control means includes a means operable to supply power to the motor when the switch means is closed.
 30. A lift apparatus for use with a structure having an upper portion and lower portion comprising: a carriage, upright track means locatable adjacent to the structure for guiding the carriage up and down in an upright path, means for attaching the track means to the structure comprising a plurality of members, each member having a slot, attaching means angularly adjustable relative to the structure for connecting the member to the structure, fastening means extended through said slot and attached to the track means, winch means mountable on the lower portion adjacent to the one side of the track means for moving the carriage, said winch means having rotatable drum means, reversible drive means drivably connected to said drum means to rotate the drum means, cable means connected to the drum means and carriage, means mountable on the upper portion adjacent to the upper end of the track means for accommodating the cable means, said cable means extended upwardly from the drum means over the means adjacent to the upper end of the track means and downwardly to the carriage whereby on operation of the drive means in one direction the drum means rotates to wind the cable on the drum means so that the carriage is moved upwardly in the upright path and on operation of the drive means in the opposite direction the drum means rotates to unwind the cable from the drum means so that the carriage moves downwardly in the urpight path.
 31. The apparatus of claim 30 wherein: the track means comprises a pair of upright tracks, each track having side flanges and a base, said base having upright groove means for accommodating a portion of the means for attaching the track means to the structure. 